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From: Juan Quintela <quintela@redhat.com>
In-Reply-To: <1364314072-2474-5-git-send-email-stefanha@redhat.com> (Stefan
	Hajnoczi's message of "Tue, 26 Mar 2013 17:07:52 +0100")
References: <1364314072-2474-1-git-send-email-stefanha@redhat.com>
	<1364314072-2474-5-git-send-email-stefanha@redhat.com>
Date: Tue, 26 Mar 2013 17:38:55 +0100
Message-ID: <87a9pqkteo.fsf@elfo.elfo>
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Subject: Re: [Qemu-devel] [PATCH 4/4] chardev: clear O_NONBLOCK on
	SCM_RIGHTS file descriptors
Reply-To: quintela@redhat.com
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To: Stefan Hajnoczi <stefanha@redhat.com>
Cc: Anthony Liguori <aliguori@us.ibm.com>, david.pravec@nethost.cz, mprivozn@redhat.com, Corey Bryant <coreyb@linux.vnet.ibm.com>, qemu-devel@nongnu.org

Stefan Hajnoczi <stefanha@redhat.com> wrote:
> When we receive a file descriptor over a UNIX domain socket the
> O_NONBLOCK flag is preserved.  Clear the O_NONBLOCK flag and rely on
> QEMU file descriptor users like migration, SPICE, VNC, block layer, and
> others to set non-blocking only when necessary.
>
> This change ensures we don't accidentally expose O_NONBLOCK in the QMP
> API.  QMP clients should not need to get the non-blocking state
> "correct".
>
> A recent real-world example was when libvirt passed a non-blocking TCP
> socket for migration where we expected a blocking socket.  The source
> QEMU produced a corrupted migration stream since its code did not cope
> with non-blocking sockets.
>
> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

Acked-by: Juan Quintela <quintela@redhat.com>